During the past two decades, large, high-density, high-input/output (I/O) electronic interconnect SMT (surface mount technology) packages such as ceramic column grid arrays (CCGAs) have increased usage in avionics hardware of NASA projects. The test boards built with CCGA packages are expensive and often require rework to replace reflowed, reprogrammed, failed, or redesigned CCGA packages. Theoretically, a good rework process should have a similar temperature- time profile as that used for the original manufacturing process of solder reflow. A multiple rework process may be implemented with CCGA packaging technology to understand the effect of the number of reworks on the reliability of this technology for harsh, extreme, thermal environments.

Optical Photographs of the fatigued solder joints in a 1st Reworked CCGA 624 package after 1,026 thermal cycles of –185 to +125 °C.
CCGA 624 packages have been increasing in use based on their advantages such as high interconnect density, very good thermal and electrical performance, and compatibility with standard surface-mount packaging assembly processes. Reworked CCGA packages are used in space applications such as logics and microprocessor functions, telecommunications, flight avionics, and payload electronic assemblies. As these packages tend to have less solder joint strain relief than leaded packages, the reliability of reworked CCGA-624 packages is very important for short- and long-term space missions.

In general, reliability of the assembled electronic packages reduces as a function of number of reworks, and the extent of reliability loss is not known yet. A CCGA rework process has been implemented to design a daisy-chain test board consisting of 624 packages. Reworked CCGA interconnect electronic packages of printed wiring polyimide boards have been assembled and inspected using non-destructive x-ray imaging and optical microscope techniques. The assembled boards after first rework were subjected to extreme temperature thermal atmospheric cycling to assess their reliability for future deepspace mission environments. The resistance of daisy-chained interconnect sections was monitored continuously during thermal cycling to determine intermittent failures. This test data shows a limitation of these reworked CCGA 624 packages for various projects. This research has reported the reliability study of CCGA 624 packages down to –185 °C and up to +125 °C.

This work was done by Rajeshuni Ramesham of Caltech for NASA’s Jet Propulsion Laboratory. NPO-49083

Topics:
Aerodynamics Drag Electronics & Computers Hardware Imaging and visualization Joining Logistics Manufacturing processes Materials handling Optics Packaging Parts Reliability Research and development
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Reworked CCGA-624 Interconnect Package Reliability for Extreme Thermal Environments

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NASA Tech Briefs Magazine

This article first appeared in the February, 2014 issue of NASA Tech Briefs Magazine (Vol. 38 No. 2).

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Overview

The document discusses the reliability of reworked ceramic column grid array (CCGA) surface mount technology (SMT) packages, specifically focusing on the CCGA-624 and CCGA-717 packages, in extreme thermal environments. Conducted by NASA's Jet Propulsion Laboratory (JPL), the research aims to enhance the reliability of electronic interconnects used in avionics hardware for NASA projects, particularly for deep space missions that experience harsh thermal conditions.

Over the past two decades, the use of high-density CCGA packages has increased in avionics, but these packages are expensive and often require rework due to failures or redesigns. The study emphasizes the importance of developing a reliable rework process that mimics the original solder reflow manufacturing process. The research investigates how multiple reworks affect the reliability of CCGA packages, particularly under extreme temperature cycling from -185°C to +125°C.

The experimental setup involved assembling reworked CCGA packages and subjecting them to rigorous testing. The test boards were monitored for electrical continuity and resistance changes during thermal cycling. Notably, the study found that the first reworked CCGA-624 package failed after approximately 1026 thermal cycles, while the CCGA-717 package showed no significant change in resistance under the same conditions. This indicates that while reworking can impact reliability, some packages may withstand extreme conditions better than others.

X-ray imaging and optical inspection techniques were employed to assess the integrity of the solder joints before and after thermal cycling. The results indicated that solder joints, particularly at the corners of the packages, experienced significant stress and fatigue, which could lead to failures. The research provides valuable insights into the performance of reworked CCGA packages, contributing to the understanding of their reliability in extreme environments.

Overall, this study serves as a foundational exploration into the effects of rework on CCGA package reliability, offering critical data for future aerospace applications and informing best practices for the design and testing of electronic interconnects in demanding thermal conditions. The findings are essential for ensuring the success of future NASA missions that rely on robust electronic systems in extreme environments.